Continuous casting of metal



March 12, 1963 H. E. HOTEKO 3,080,627

CONTINUOUS CASTING OF METAL Filed June 9, 1959 2 Sheets-Sheet 1 Fig.1.

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PRESSURE AMPLIFIER March 12, 1963 H. E. HQTEK I 3,080,627

CONTINUOUS CASTING OF METAL Filed June 9, 1959 2 Sheets-Sheet 2 nrroeM-Y 3,080,627 CONTINUGUS CASTING F METAL Henry Eugene Hoteko, Banbury, England, assignor to Aluminium Laboratories Limited, Montreal, Canada, a

corporation of Canada Filed June 9, 1959, Ser. No. 819,065 Claims priority, application Great Britain June 11, 1958 3 Claims. (Cl. 22-574) The present invention relates to the continuous casting of metal rod or strip by the rotating wheel method in which molten metal is poured into a mould which consists of a rotating wheel having a grooved periphery of appropriate profile closed by a metal band wrapped around part of the periphery of the wheel and moving substantially in synchronism with it. In this method the band usually meets the periphery of the wheel at a point near the top of the wheel so as to provide an entry point into which the metal is poured by means of a launder. It is desirable that the level of the pool of molten metal at the point of entry should be maintained fairly constant. The accurate control of this level is of prime importance for the production of a cast rod or strip of satisfactory surface finish and edge finish.

It is an object of the present invention to provide a means for automatically controlling the level of molten metal in a rotating wheel type continuous casting apparatus. In principle, this object is achieved by immersing a liquid level detector in the pool of metal in the groove at the top of the wheel and controlling the molten metal supply in response to the level indicated by the detector.

According to the present invention apparatus for controlling the level of molten metal in a continuous casting apparatus of the type in which a mould is formed by a rotating wheel and co-operating band comprises a. level detector member having an air inlet connection and a plurality of air outlet vents arranged at spaced intervals in said level detector so that the rate of air escape therefrom is dependent on the number of unobscured vents, said level detector member being arranged to project into the pool of metal and being connected to a source of low pressure air through a restricted aperture of such small size that the pressure of air entering the detector member is varied according to the number of unobscured vents, the detector member also being connected to an air pressure responsive device which in turn controls a means for varying the rate of metal supply to the casting wheel.

One form of apparatus devised for controlling the level of aluminium in an apparatus for continuous casting of aluminium by the casting wheel method is shown in the accompanying drawings wherein:

FIGURE 1 shows a general arrangement of the apparatus, and

FIGURE 2 is a section on a larger scale of the level detector element.

In FIGURE 1 the continuous casting apparatus consists of a rotatable casting wheel 1 which has a groove of appropriate section formed in its periphery, this groove being covered by a steel band 2 which moves round in synchronism with the casting wheel 1 and is carried on wheels 3. Molten metal from a melting furnace is poured into the groove in the wheel 1 by means of a launder 4 and the cast strip 5 is continuously drawn out from the bottom end of the casting wheel. This is a conventional arangement for producing continuously cast rod or strip and there are a number of known alternative arrangements of the grooved casting wheel and its covering band. The present invention is applicable to all such constructions.

The feature of the present invention is the control of the level of metal at the top of the mould, where the band meets the periphery of the wheel. The flow of metal in the launder is governed by a movable gate 6 which is raised and lowered by a reversible air motor 7 which, in its turn, is governed by an air pressure amplifier 8. The vertical level of the gate 6 is dependent on the pressure produced by the amplifier 8, the decrease in pressure causing a raising of the gate. Both the air motor 7 and the air pressure amplifier 8 are com-mercially available units, for example, the air motor may be a Foxboro Model No. 20E diaphragm motor lever. The air pressure amplifier 8 which may be a Foxboro Model No. 40, zero to 14" water gauge indicating controller, detects changes in the pressure of air in the air line 9 to which air is fed from a constant air pressure supply (not shown), at a low pressure of about 1 lb./sq. inch through a restricted aperture 10. The air pressure in the airline 9 is governed by the leakage therefrom through a level detector member 11 which is secured to the leading end of the launder 4. The detector member 11 is arranged to lie in an inclined position in the groove in the top of the casting wheel 1. The level detector 11 consists of a curved tube made of a material which withstands the corrosive attack of the metal being cast. That part of the tube which is intended to lie in the upper part of the mould cavity formed by the groove in the casting wheel and the co-operating band is bent to the curvature of the wheel and is preferably positioned so that its axis is equidistant from the side of the mould cavity. The tube is detachably mounted in a spring loaded block 12 which in turn is fixed to the end of the launder 4. The metal tube is connected to the air line 9 by means of a polythene tube and is provided with a series of outlet vents 1-4 which in use are arranged to lie at difiierent levels within the groove in the wheel 1, as can be seen from FIGURE 1. By correct proportion ing of the size of the restriction 10 to the vents 14 an appreciable change in air pressure in the air line 9 results from the successive closure of the vents 14. The air pressure amplifier 8 is arranged to control the air motor 7 in such a manner that an increase in air pres sure in the air line 9 is reflected in a downward movement of the gate 6 so as to reduce the fiow of metal to the casting wheel and vice versa.

The output of the air pressure amplifier may be applied to a pneumatic or pneumatic-electrical device for controlling the tilting of the furnace from which the metal is poured into the launder. This may be in place of or in addition to the control gate in the launder.

Preferably the tube has an external diameter of and an internal diameter of The restriction 10 is an orifice of about 0.060 diameter, the vents 14 are orifices of 0.030" diameter spaced /3" apart, While the lower end of the tube is terminated by a hole of 5 diameter.

It is an advantage of the apparatus of the present invention that it can be fitted to existing casting wheel apparatus without any modification to the casting wheel or steel band. It is only necessary, indeed, to arrange for the level detector element '11 to be secured to the leading end of the launder and for a movable gate to be secured in the launder or for like control means to be located elsewhere in the supply of molten metal.

I claim:

1. Apparatus for controlling the level of molten metal in a continuous casting apparatus of the type in which a mould is formed by a grooved rotating wheel and cooperating band, comprising a liquid level detector member separate from said mould having an air inlet conmention and a plurality of air outlet vents arranged at spaced intervals in said level detector so that the rate of escape therefrom is dependent on the number of unobscured vents, said level detector member being disposed within the groove at the top of said mould at the point of entry of said molten metal into said mould, said level detector member being arranged to project into the pool of metal in said mould and being connected to a source of low pressure air through a restricted orifice of such small size that the pressure of air entering the detector member is varied according to the number of unobsc-ured vents, means for controlling the rate of metal supply to the wheel and means responsive to the air pressure in the detector member for controlling the metal supply control means.

2. Apparatus according to claim 1, wherein the detector member is connected to an air pressure amplifier which in turn controls a movable gate for controlling the flow of metal to the casting wheel.

3. Apparatus in accordance with claim 1 wherein said detector member is disposed within said groove substantially equidistant of the sides of said groove.

References Cited in the file of this patent UNITED STATES PATENTS 1,139,888 Mellen May 18, 1915 1,651,678 Davis Dec. 6, 1927 2,659,948 Properzi Nov. 24, 1953 2,889,596 Savage June 9, 1959 2,905,989 Black Sept. 29, 1959 FOREIGN PATENTS 461,024 Italy Jan. 10, 1951 777,354 Great Britain June 19, 1957 

1. APPARATUS FOR CONTROLLING THE LEVEL OF MOLTEN METAL IN A CONTINUOUS CASTING APPARATUS OF THE TYPE IN WHICH A MOULD IS FORMED BY A GROOVED ROTATING WHEEL AND COOPERATING BAND, COMPRISING A LIQUID LEVEL DETECTOR MEMBER SEPARATE FROM SAID MOULD HAVING AN AIR INLET CONNECTION AND A PLURALITY OF AIR OUTLET VENTS ARRANGED AT SPACED INTERVALS IN SAID LEVEL DETECTOR SO THAT THE RATE OF AIR ESCAPE THEREFROM IS DEPENDENT ON THE NUMBER OF UNOBSCURED VENTS, SAID LEVEL DETECTOR MEMBER BEING DISPOSED WITHIN THE GROOVE AT THE TOP OF SAID MOULD AT THE POINT OF ENTRY OF SAID MOLTEN METAL INTO SAID MOULD, SAID LEVEL DETECTOR MEMBER BEING ARRANGED TO PROJECT INTO THE POOL OF METAL IN SAID MOULD AND BEING CONNECTED TO A SOURCE OF LOW PRESSURE AIR THROUGH A RESTRICTED ORIFICE OF SUCH SMALL SIZE THAT THE PRESSURE OF AIR ENTERING THE DETECTOR MEMBER IS VARIED ACCORDING TO THE NUMBER OF UNOBSCURED VENTS, MEANS FOR CONTROLLING THE RATE OF METAL SUPPLY TO THE WHEEL AND MEANS RESPONSIVE TO THE AIR PRESSURE IN THE DETECTOR MEMBER FOR CONTROLLING THE METAL SUPPLY CONTROL MEANS. 